Air Information Publications — Page 16, Lesson 24

I want to walk you through two important sections from the UK AIP — the Aeronautical Information Publication — that you'll use every time you plan a flight. We're looking at the ENR, or En Route, part of the AIP. First, let's talk about name code designators for significant points. When you look at a chart, you'll see positions that aren't marked by a radio navigation aid on the ground. For those positions, we use a coded designator of up to five characters — you can see examples like ABDAL, ABSIL, ACORN, and so on in the table. Each of these five-letter codes is a name for a specific point in the sky. Now, even though there's no navaid at that exact point, we still need to define its position precisely. So each of these points is defined by a radial and a bearing from a co-located VOR/DME — that's a VHF Omnidirectional Range combined with Distance Measuring Equipment. Let me read you one example from the table: ABDAL has coordinates 512646N 0015149W, and its purpose is "Cotswold CTA - Arrivals to Bristol, Cardiff & Filton." The definition is given as "CPT VOR/DME fix, 268°/24 NM." That means ABDAL is located on the 268-degree radial from the CPT VOR/DME, at a distance of 24 nautical miles. So you can see how every one of these significant points is tied back to a real navaid. Now let's move to the next section — Navigation Warnings. This is critical for safety. When you're planning any flight, whether VFR or IFR, at low or high Flight Levels, you must take into account several categories of hazards. The AIP lists them clearly: - Prohibited, Restricted and Danger Areas — these are airspace volumes you either cannot enter or must have special permission to enter. - Military Exercise and Training Areas — where military aircraft are operating. - Other Activities of a Dangerous Nature, such as High Intensity Radio Transmissions. - Air Navigation Obstacles En Route, like bridges and chimneys. - Aerial Sporting and Recreational Activities. Let's focus on the first category — Prohibited, Restricted and Danger Areas — and specifically look at the table for Danger Areas. The table gives you, for each area, an identification code, its name, lateral limits defined by coordinates, an upper limit in feet, a lower limit in feet, and then activity details, hours of operation, and contact frequencies. Take the first example: EG D001 Trevose Head. Its lateral limits are given as a series of coordinate pairs that trace the boundary. The upper limit is ALT 100 — that means altitude 100 feet — and the lower limit is SFC, meaning the surface. The activity is helicopter exercises including winching, operated by the Air Force Department. The hours are Monday to Thursday 0800 to 2359, Friday 0800 to 1800. The service frequency is DACS — that stands for Danger Area Crossing Service — on St Mawgan APP 126.500 MHz when that unit is open. At other times, you use DAAIS — Danger Area Activity Information Service — on London Information 124.750 MHz. Now look at the second example: EG D003 Plymouth. This one goes up to ALT 55,000 feet from the surface, but there's a note: "Subject to co-ordination procedures above ALT 22,000." So below 22,000 feet it's active as shown, but above that altitude you need special coordination. The activity includes ship exercises, target towing, firing, and pilotless target aircraft — operated by the Navy Department. The hours are Monday to Thursday 0800 to 2359, Friday 0800 to 1600, and as notified. The service is DACS on Plymouth Military 121.250 MHz when open; otherwise London Mil via London Information on 124.750 MHz. And there's a pre-flight information phone number: Plymouth Operations on 01752-557550. So the key takeaway here is: before every flight, you must check these navigation warnings. You need to know which danger areas are active, their vertical and horizontal limits, what times they're active, and which frequency to call for crossing services or information. This is not optional — it's a safety requirement built into your flight planning process.